Limiter and interrupter for alternating electric currents.



APPLICATION FILED MAR. 11,1912.

Patented Jan. 5, 1915.

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UNITED STATES PATENT OFFICE.

ALFRED W. BURKE, OF WILKINSBURG, PENNSYLVANIA.

LIMITER AND INTERRUPTER FGR- ALTERNATING ELECTRIC CURRENTS.

Application filed March 11, 1912.

To all whom it may concern. A

Be itknown that I, ALFRED W. BURKE, a subject of the King of Great Britain, residing at ilkinsburg, in the county of Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in Limiters and Interrupters for Alternating Electric Currents, of Which the following is a specification.

In many electric-lighting systems, it is customary to charge the individual consum crs at a rate based on the maximum number of lights used, and it is then desirable to provide some means for preventing the use of a greater number of lights than that paid for. Various devices have been invented for this purpose, in Which the lighting circuit of the individual consumer is automatically opened when the current consumed exceeds that paid for, but such devices are apt to deteriorate and become inoperative by reason of the heavy are formed at the contacts When the circuit is opened; furthermore, the complete extinguishing of all of the lights, Which may be due to the accidental overconsumption of current, is an unnecessary hardship to the consumer.

The present invention is an apparatus, one of Which is to be placed in each individual consuming circuit, for greatly decreasing the current supplied, or causing it to fluctuate, when the consumption exceeds the predetermined amount, thereby causing the lamps to become dim or flicker, Without opening the lighting circuit or changing its ohmic resistance.

The apparatus comprises a transformer having one of two separate windings, or a portion of a single Winding, permanently in the lighting circuit, and a second Winding, or all of the single Winding, normallv shortcircuited but capable of being opened, either automatically or manually, thereby increasing the reactance of the winding in series with the lighting circuit and correspondingly decreasing the current supplied to the lamps. In the preferred apparatus, an automatic electromagnetic device is provided for intermittently opening and closing the .circuit of the normally short-circuited Winding, thereby causing the lighting current to pulsate and the lamps to flicker, indicating to the consumer the necessity of extinguishing one or more lamps.

Referring to the accompanying drawing Figure 1 is a diagrammatic illustration of Specification of Letters Patent.

Patented Jan. 5, 1915.

Serial No. 682,884.

an individual lighting circuit and interrupting apparatus employing an autoor single- Wound transformer, having a portion of its Winding in the lighting circuit and its entire Winding short-circuited through an automatic electromagnetic interrupter; Fi 2 is a diagrammatic illustration of a lighting circuit and interrupting apparatus employing a double-Wound transformer, one short Wind ng being in the lighting circuit and the other longer Winding being short-circuited through an automatic electromag netic interrupter and also through another interrupter, the electromagnet of which can be manuallv energized; and Figs. 3 and i are side and end elevations, IGSDQCtlYQlV, of the automat c interrupter used in the apparatus of Fig. 1.

Fig. 1 illustrates an individual lighting circuit comprising mains 1, 2 feeding a series of lamps 3. The auto-transformer 4 of the interrupting apparatus has a Winding 5, constituting the secondary, which may consist, for example, of one hundred turns. A portion 6' of the Winding, constituting the primary, consisting of for example, ten turns, is shoWn as interposed in series with and constituting a part of the main 2. The ends of the secondary Winding 5 are normally short-circuited by Wires 7, 8 and the automatic electromagnetic interrupter 9. With the specified ratio of turns in the lighting circuit and interrupter circuit, ten to one hundred, an alternating current of ten amperes flowing through the lamps 3 induces a current of about one ampere through the entire secondary Winding 5 and interrupter. If the electromagnet of the interrupter is Wound to open its short circuit When it passes a current of more than one ampere, the opening of the secondary winding 5 immediately causes the current fed through the primary Winding 6 to be greatly diminished, therebv nearly extinguishing the lamps 3 and de nergizing the magnet of the interrupter. The secondary winding 5 is thereby again short-circuited, and if the current consumed by the lamps remains in excess of ten amperes the supply of current to the lamps is intermittently greatly decreased, causing them to flicker.

The specific interrupter indicated in Fig. 1 is shown in detail in Figs. 3 and 4. It comprises an electro-magnet 10, one end of the Winding of which is connected to the Wire 7 leading from one end of the auto transformer coil 5. The other end of the magnet winding is connected to a thin flexible wire 11. Beneath the electrornagnet 10 is a horizontal glass tube 12, supported at its middle by opposite trunnions 13. This tube contains a layer 14 of mercury, which, when the tube is in horizontal position, covers and short-circuits the end 15 of the flexible wire 11, extending through and sealed into one end of the tube, and the end of a flexible wire 16, sealed into a bulb at the bottom of the tube beneath the trunnions and connected by the wire 8 to the other end of the auto-transformer winding 5. The magnet has a core with an extended polepiece 17. Fixed on the glass tube 12 near the end which receives the wire terminal 15 is a metal band 18 which carries an armature 19, in proximity to the pole-piece 17. Fixed to and extending from the lower part of the band 18 is a stem 20 carrying a plunger 21 which loosely enters a receptacle 22 containing a body of liquid 23. The plunger 21 has holes 24 controlled by movable shutters 25, and by varying the size of the openings through the plunger the resistance to its movement through the liquid can be varied. In operation, when the current through the electromagnet 10 exceeds the predetermined value, the armature 19 is attracted by the pole-piece 17 and the tube 12 is tilted so that the mercury 1 L runs down out of contact with the terminal 15, opening the circuit of the auto-transformer winding 5. The electromagnet being thereby deenergized, the tube again slowly resumes its horizontal position, its speed of oscillation being controlled by the dash-pot device, the circuit is re-closed, the electromagnet reenergized and the circuit again broken. The lamps are thereby caused to flicker until the current through the auto-transformer winding 5 and magnet 10 is reduced to a value below one ampere, necessitating the current supplied to the lamps to be reduced below ten amperes. The auto-transformer winding 5 may be provided with various taps including different numbers of turns, providing a primary of greater or less turns, enabling an interrupter which operates with any given current, say one ampere, to be employed with lighting circuits using different amounts of current. For example, a tap 26 is shown in Fig. 1, providing a primary which includes twenty turns of the winding 5, enabling the same interrupter to be used for a maximum current-consumption of five, instead of ten, amperes.

Qopies ot this patent 'maybe ootained for The ap aratus illustrated in Fig. 2 is similar to that shown in Fig. 1, except that the transformer has separate windings, the short primary winding 6 being interposed in the lighting circuit and the terminals of the long secondary winding 27 being connected to the automatic electromagnetic interrupter 28. A second interrupter 29 is also shown in the circuit of winding 27, the electromagnet of which can be manually energized by a separate circuit 30. Such manual control, from a circuit extending for example to the power-house, is desirable where the consumption of current is limited to a certain period of the day, enabling the lamps to be rendered useless at other times.

I claim 1. In combination, a transformer having a short primary winding interposed in a circuit receiving current and a normally shortcircuited long secondary winding, and automatic means, energized by the current in said long winding, for opening the shortcircuit.

2. In combination, a transformer having a short primary winding interposed in a circuit receiving current and a normally shortcircuited long secondary winding, and an electromagnetic interrupter energized by the induced current in said long winding constructed to open the short-circuit when the inducing current in the work-circuit exceeds a predetermined value.

3. In combination, a transformer having a short primary winding interposed in a. circuit receiving current and a normally shortcircuited long secondary winding, and an electromagnetic interrupter constructed to repeatedly open and close the ShOIt'ClI'CUilt when the current in the work-circuit exceeds a predeterm ned value.

4. In combination. a transformer having a short primary winding interposed in a circuit receiving current and normally shortcircuited long secondary winding, and an electromagnetic interrupter, energized by the induced current in said long winding, constructed to repeatedly open and close the short-circuit when the inducing current in the work-circuit exceeds a predetermined value.

In testimony whereof I aflix my signature in presence of two witnesses.

ALFRED W. BURKE.

WVitnesses EUGExE A. BYRNES, C. N. FowLEn.

ents each. by addressing the Commissioner of Patents. Washington,.D.C." r 

